Clamping fixture for detachably particular a disc

ABSTRACT

A clamping fixture for detachably fixing a disc-like tool to a spindle in cooperation with a tool-fixing member, and comprising a flange member for clamping the tool between the flange member and the tool-fixing member and a supporting element for attaching the flange member to the spindle in a torque-transmitting relationship and having an annular part, the flange member being axially and rotationally displaceable relative to said annular part, the annular part having a first end surface to be axially supported on the spindle and a second end surface and the flange member having an end surface bearing on the second end surface of the annular part with the second end surface of the annular part and the end surface of the flange member having a plurality of complementary sloping end surface portions inclined toward the spindle axis and defining a wedge angle having a size lying in a self-locking range, and the annular part including a plurality of stop surfaces extending substantially parallel to the spindle axis adjoining a respective sloping end surface portions of the second end surface at lower ends of thereof end portions and a plurality of drive surfaces extending parallel to respective stop surfaces in spaced relationship thereto and arranged in front of upper ends of respective sloping end portions of the second end surface, the flange member having a respective plurality of stop dogs defining locking surfaces engaging respective stop surfaces of the annular part upon the axial displacement of the flange member and relief of the clamping pressure, and a respective plurality of surfaces engageable by respective drive surfaces of the annular part when the tool is clamped between the flange member and the tool-fixing member.

BACKGROUND OF THE INVENTION

The invention relates to a clamping fixture for detachably fixing atool, in particular a disc. Clamping fixtures, in particular fordisc-shaped tools are suitable particularly for portable power handtools, and in this respect in particular for grinding hand power tools.A clamping fixture has been disclosed (German Patent Specification No.3,012,836) in which one flange, which is arranged on the side of thetool pointing towards the housing of the power hand tool, isdisplaceable relative to the spindle and is coupled to the latter insuch a way as to transmit torque. In this arrangement, this rearsupporting flange is supported against axial displacement in an axialend position via a spindle shoulder forming a supporting element for thesupporting flange. The other flange, which can be screwed onto the endof the spindle, consists of a nut having a separate clamping elementwhich has a roughly hat-shaped cross-section and is supported axiallyagainst the flange of the clamping nut via a coil spring. When thisclamping nut is screwed on and tightened, the pot-shaped clampingelement is pressed axially against the tool via an axially compressedspring, and the tool is thereby tightened against the flange on thespindle side, the end face of a cylindrical extension of the clampingnut coming to bear directly on a facing axial side of the rear flangeand, during further tightening of the clamping nut, this rear flange onthe spindle side being tightened together with the clamping nut, ifnecessary until the rear flange comes to bear axially on the spindleshoulder surface forming the supporting element. In an angle grinder,the grinding disc is thereby supposed to be mounted with a predeterminedcontact pressure, and this contact pressure, is supposed to be ensured.This clamping fixture is also intended to enable a quick and simpleexchange of the grinding disc and, at the same time, avoid overloadingof the power hand tool, in particular the angle grinder. This isbecause, if the torque acting on the grinding disc is too great, thegrinding disc stops, while the rear flange and also the clamping nuthaving the clamping member perform a relative movement thereto. Theeffect of the clamping nut automatically tightening further inoperation, which otherwise makes it considerably more difficult toloosen the clamping nut when changing the grinding disc, is counteractedwith this clamping fixture. Nonetheless, loosening of the clamping nutis here only possible with the assistance of a special auxiliary tool,the spindle, depending on the design of the machine, having to beappropriately counterheld by a second auxiliary tool, e.g. a spanner.

SUMMARY OF THE INVENTION

The object of the invention is to make possible a tool change withoutany auxiliary tool, which tool change, in addition, can be performedquickly and safely. A further advantage is that powered hand toolsalready existing can also be changed over without considerable redesign.For example, a simple substitution of the existing rear supportingflange for an annular part having an adapted flange is sufficient forthis purpose. The front clamping nut is taken over unchanged in a knownmanner so that recourse can be made here to standardized, cost-effectiveparts. At the same time, it is still possible in especially stubborncases, e.g. in the event of a rusted-in clamping nut, for a spanner tobe placed thereon, and the clamping nut can be released with thisauxiliary tool. The rear annular part is in a rotationally fast,positive-locking connection with the spindle so that relevantregulations are complied with. Furthermore, it is of advantage that theclamping fixture is not arranged on the working side of the tool but inthe area between the tool and the bearing flange on the housing side, sothat any risk of damage, e.g. chafing on the workpiece, is countered.This also avoids an axial projection on the working side of the tool,which axial projection could impair the work.

The novel features which are considered as characteristic for theinvention are set forth in the appended claims. The invention itself,however, both as to its construction so to its mode of operation,together with additional objects and advantages thereof, will be bestunderstood from the following description of preferred embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows schematically an axial longitudinal partial cross-sectionalview of a clamping fixture according to the invention as part of anangle grinder having a mounted grinding disc,

FIG. 2 shows schematically an enlarged side view, of a detail of theclamping fixture according to the invention with a tool clamped inplace,

FIG. 3 shows a side view corresponding to that in FIG. 2, but with aloosened tool,

FIG. 4 shows schematically a partially cross-sectional plan view alongthe line IV--IV in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 schematically shows the lower part of a portable power hand toolwhich is designed, for example, as an angle grinder and has a spindle 10which is motor-driven via a gearing and, at the end, merges via anannular shoulder 11 into a cylindrical step 12 of smaller diameter andthen into an end-side threaded step 13 having an external thread 14. Thespindle 10 serves to drive a tool 15 which consists, for example, of thegrinding disc indicated or another tool disc, a rubber plate or thelike. The tool 15 is mounted axially and clamped in place between twoflanges 16 and 17. The flange 17 thereof sitting on the spindle end isdesigned as a conventional clamping nut 18 which has a hub part 19,adjoining the flange, and is provided with a through internal thread 20in the interior with which the clamping nut 18 is screwed onto thethreaded step 13. The tool 15, during fixing, is centered on the outerperipheral surface of the hub part 19.

The other flange 16 is displaceable relative to the spindle 10 and, in amanner yet to be described, is coupled to the spindle 10 in such a wayas to transmit torque. It is secured against axial displacement via asupporting element 21 and, relative to the latter, can be relieved ofthe clamping pressure for the tool 15. The supporting element 21consists of an annular part 22 which in cross-section is roughly in theshape of an inverted pot and has a base 23 and a cylindrical part 24.With the base 23, the annular part 22 is supported axially against theannular shoulder 11 and centered radially on the cylindrical step 12.Owing to matching shaped surfaces, e.g. two flats parallel to oneanother, on the spindle 10 and in the base 23, the annular part 22 is ina rotationally fast, positive-locking connection with the spindle 10,which drives it along in a rotationally fast manner in the direction ofrotation according to arrow 25 when the motor is switched on.

The flange 16 essentially consists of a relatively flat disc. Withregard to the spindle 10, it is axially displaceable and rotatably heldwithin limits on the outer peripheral surface of the hub part 19. Theannular part 22 and the flange 16 are coupled by a spring 26 which ishere designed as a torsion spring and of which one end 27 acts on theannular part 22 and the other end 28 acts on the flange 16. In FIGS. 2and 3, for the purpose of clarification, a spring is instead only shownschematically, which spring acts with the end 18 on the flange 16 andloads the latter in a spring-elastic manner relative to the annular part22 in the direction of the arrow 29 indicated.

On the end faces 30 and 31 facing one another axially, the annular part22 and the flange 16 respectively have a plurality of sloping surfaces32 and 33 respectively, e.g. three, which follow one another in theperipheral direction and are inclined to the left and with which theflange 16 and the annular part 22 bear axially against one another. Inthis arrangement, the sloping surfaces 32 of the annular part 22 arelocated on the end face 30, pointing towards the flange 16, of thecylindrical part 24.

The wedge angle of both sloping surfaces 32, 33 is selected to be ofsuch a size that it lies in the self-locking range. A step surface 34directed parallel to the axis in each case adjoins the respectivesloping surface 32 of the annular part 22 towards the top wedge end.During the movement of the flange 16 relative to the annular part 22towards the wedge bottom of the sloping surfaces 32, 33 and during theaxial relief, consequently accompanying this movement, of the clampingpressure, the flange 16, in each case with locking surfaces 35 allocatedto the step surfaces 34, strikes against the step surfaces with thepivoting angle being limited. FIG. 3 shows this state, in which theclamping fixture is released and thus the screwed-on flange 17 isrelieved of the axial clamping pressure exerted on the tool 15 by theflange 16.

The flange 16 has stop dogs 36 which adjoin the respective slopingsurface 33 at its end located towards the wedge bottom and are directedparallel to the axis and whose end face adjacent to the sloping surface33 is in each case designed as a locking surface 35. The opposite endface of each stop dog 36 of the flange 16 is designed as an engagingsurface 37 roughly parallel thereto. The annular part 22 has drivingsurfaces 38 which are located in front of each sloping surface 32 in theperipheral direction, are roughly parallel to the axis and, when tool 15is clamped (FIG. 2), in each case strike against an allocated engagingsurface 37 of the stop dog 36 while driving the flange 16 along.

The step surfaces 34 and driving surfaces 38, running at a distancetherefrom in the peripheral direction, of the annular part 22 are formedby the two end faces of respective catch recesses 39 which consist ofapertures in the wall of the cylindrical part 24. The catch recesses 39adjoin each sloping surface 32 at its end towards the wedge top and areopen axially and in the direction of the flange 16. In this arrangement,the opening width, measured in the peripheral direction, of each catchrecess 39 is greater than the width of each stop dog 36 engagingtherein.

As shown in particular by FIG. 4, rolling bodies 40 are arranged betweenthe sloping surfaces 32 and 33, bearing axially against one another, ofthe annular part 22 and the flange 16, which rolling bodies 40 turn thesliding friction between the sloping surfaces 32, 33 into a rollerfriction and thus substantially reduce the friction. The rolling bodies40 here consist of balls which are inserted into recessed grooves 41 inthe sloping surfaces 32.

The flange 16 is fixed to, e.g. screwed into, a cylindrical sleeve 42which surrounds it. The cylindrical sleeve 42 also extends axially overthe cylindrical part 24 of the annular part 22, which, at the end remotefrom the tool 15, is overlapped by an axial stop in the form of anannular shoulder 43. In this way, the flange 16, together with thecylindrical sleeve 42 on the annular part 22, is secured againstloosening in the axial direction away from the annular part 22. Theflange 16 and the annular part 22 are held together by means of thecylindrical sleeve 42.

Furthermore, the clamping fixture has at least one detachable lockingdevice 44 via which the flange 16, in the position which is shown inFIG. 2 and in which the tool 15 is clamped in place, is secured in apositive-locking manner with regard to the annular part 22. The lockingdevice 44 has a tongue 45 which, with one end, is fixed by means ofscrew 46 to the annular part 22, and in fact on the side which pointstowards the flange 16. The tongue 45 is directed roughly radially. Itacts roughly like a spring leaf and is in addition pressed down by meansof a spring 47 in the form of a cylindrical coil spring in FIGS. 2 and3. To mount and center the end of the spring 47, the tongue 45 containsa sunk portion 48. The spring 47 acts at a relatively large radialdistance from the fixing point of the tongue 45 by the screw 46. Withregard to the cross-sectional thickness, the tongue 45 is dimensioned insuch a way that it is bent down like a spring tongue in FIGS. 2 and 3under the action of the relaxing spring 47 and can be bent up in theopposite direction thereto by means of manual actuation with the spring47 being compressed. It will be understood that this tongue 45 can alsobe formed, e.g. bent, in such a way that, in the position shown in FIG.2 and moved down in the axial direction, it is stress-free and relieved,and can be raised axially upwards against the action of the spring 47into the position shown in FIG. 3.

The tongue 45 is mounted in a recessed portion 49 which runs in the basearea of the catch recess 39 and, in the area of the spring 47, isprovided with a cavity 50 accommodating and centering this end.

The width of the tongue 45 and the stop dog 36 together is selected soas to be approximately as large as the overall width of the catch recess39 so that, in the clamped state of the tool 15 according to FIG. 2, thestop dog 36 and the tongue 45 find space next to one another inside thecatch recess 39. In the position of the flange 16 in which the tool 15is clamped in position, the tongue 45 thus engages into the catch recess39, and in fact between its step surface 34 and the locking surface 35of the stop dog 36. In this way, the tongue 45, in this position (FIG.2), ensures that the stop dog 36, with its engaging surface 37, bearsagainst the driving surface 38 of the annular part 22. If the spindle 10is driven in the working direction according to arrow 25 and the annularpart 22 is thus driven in the same way, the latter also drives theflange 16 along via the driving surface 38, which strikes against theengaging surface 37 of the stop dog 36. As a result, the annular part 22and the flange 16 are slid up along the sloping surfaces 32, 33 and arethereby thrust apart axially. This axial expanded position (FIG. 2) issecured by the tongue 45, even if, for example, the motor of the powerhand tool is switched off and the spindle 10 is thus stopped relativelysuddenly, while the flywheel moment, still acting on the tool 15, in thesame direction according to arrow 25 could tend to rotate the tool 15together with the two flanges 16, 17 and relative to the annular part 22in the drive direction according to arrow 25, resulting in undesiredloosening of the tool 15. This is prevented by the tongue 45, whichsupports the stop dog 36 with regard to the step surface 34.

In addition, if no tool 15 is mounted, the spring 26 also causes theflange 16 and the annular part 22 to rotate relative to one another insuch a way that both parts slide up on the sloping surfaces 32, 33 andare thereby thrust apart axially.

If the tool 15 is to be removed and changed, the annular part 22 isrotationally locked via suitable means, which can be done by appropriatelocking of the spindle 10, e.g. by means of a spindle-locking deviceintegrated in the powered hand tool. The friction in the gearing and upto the motor may possibly also be sufficient to prevent the spindle 10from rotating at least within limits in the direction of the arrow 25.Here, by taking hold of the end of the tongue 45 which can be grippedfrom outside, one hand lifts the tongue 45 against the action of thespring 47 into the position shown in FIG. 3 in which the tongue 45 movesinto the recessed portion 49, which is deep enough for the tongue 45 tonow release the stop dog 36, which, with its axially facing end, cantravel over the tongue 45. The tool 15 is then rotated by hand in thesame direction according to arrow 25, that is, anti-clockwise. In theprocess, the flange 17 and the flange 16 are also driven along via thefriction. The rotation of the flange 16 in this direction causes itssloping surfaces 33 to slide towards the wedge bottom of the slopingsurfaces 32 of the rotationally locked annular part 22, this slidingmovement, because of the rolling bodies 40, turning into a rollingmovement having reduced rolling friction. During this relative rotationof the flange 16 with regard to the annular part 22 towards the wedgebottom of the sloping surfaces 32, the flange 16 moves axially in thedirection of the annular part 22, which leads to a corresponding axialrelaxation. The clamping nut 18 can thereupon be easily unscrewedcompletely by hand. The sliding movement of the flange 16 with thesloping surfaces 33 towards the wedge bottom of the sloping surfaces 32is limited by the locking surfaces 35 on one side of the stop dogs 36striking against the step surfaces 34 on the allocated side of therespective catch recess (FIG. 3). As soon as the releasing torque isreduced to zero when the tool 15 is being released, the spring 26 isable to rotate the flange 16 relative to the annular part 22 so that thesloping surfaces 33 of the flange 16 slide towards the wedge top on thesloping surfaces 32 of the annular part 22, and the two parts 16, 22 areagain thrust apart axially. This movement is limited by the stop dogs36, with their engaging surfaces 37, striking against the respectivelyallocated driving surfaces 38 of the respective catch recess 39. Eachstop dog 36 is then located in the position according to FIG. 2 in whichthe tongue 45, blocked beforehand by means of the stop dog 36, canautomatically move out of the recessed portion 49 and snap into theintermediate space between each step surface 34 and locking surface 35under the action of the relaxing spring 47. This thrust-apart positionis thus secured in a positive-locking manner. In this position, a newtool 15 can be inserted and clamped in place. In the process, it issufficient for the clamping nut 18 to be screwed down gently and thusfor the new tool 15 to be gently tightened, since, when the motor issubsequently switched on, the tool 15 tightens automatically inoperation.

The rolling bodies 40 arranged between the sloping surfaces 32, 33resting on one another have the advantage that the face friction presentbetween the two is reduced to a rolling friction and is thus virtuallynegligibly small.

The clamping fixture described is simple, cost-effective and quick, safeand easy to handle. It enables the tool 15 to be quickly and safelychanged without requiring additional special tools for this purpose. Afurther advantage is that existing power hand tools, in particulargrinding power tools, can also be subsequently equipped with thisclamping fixture without considerable further redesign. For thispurpose, only the existing rear flange, in general, needs to beexchanged for the unit which consists of the annular part 22 and flange16, held together via the cylindrical sleeve 42. In the process, the,e.g. standardized, clamping nut 18 present in other machines will beretained unchanged, as will a rotationally fast, positive-lockingconnection between the part supporting the tool 15 and the spindle 10.Thus corresponding relevant regulations are complied with. It is alsopossible in particularly stubborn cases, e.g. in the slightly rustedstate, to loosen the clamping nut 18 in a conventional manner by meansof an auxiliary tool. The clamping fixture is not restricted to grindingdiscs as tool 15. On the contrary, other tools, e.g. cup wheels,brushes, rubber plates or the like can also be clamped without a tool.

While the invention has been illustrated and described as embodied in aclamping fixture for detachably fixing a disc-like tool, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:
 1. A clamping fixture for detachablyfixing a disc-like tool to a spindle in cooperation with a tool-fixingmember, said clamping fixture comprising a flange member for clampingthe tool between said flange member and the tool-fixing member; asupporting element for attaching said flange member to the spindle in atorque-transmitting relationship and having an annular part; and atorsion spring having two ends attached to said flange member and saidannular part, respectively, for coupling said flange member with saidannular part for relative axial and rotational displacementtherebetween, said annular part having a first end surface to be axiallysupported on the spindle and a second end surface, and said flangemember having an end surface bearing on said second end surface of saidannular part, said second end surface of said annular part and said endsurface of said flange member having a plurality of complementarysloping end surface portions inclined toward the spindle axis anddefining a wedge angle having a size lying in a self-locking range, saidannular part including a plurality of stop surfaces corresponding innumber to a number of sloping end surface portions thereof and extendingsubstantially parallel to the spindle axis with each stop surfaceadjoining a respective sloping end surface portion of said second endsurface at a lower end of said respective sloping end portion and aplurality of drive surfaces corresponding in number to a number ofsloping end surface portions of said annular part, extending parallel torespective stop surfaces in spaced relationship thereto with each drivesurface arranged in front of an upper end of a respective sloping endportion of said second end surface, said flange member having arespective plurality of stop dogs extending parallel to the spindle axisat lower ends of respective sloping end surface portions of said flangemember and defining each a locking surface engaging a respective stopsurface of said annular part upon the axial displacement of said flangemember and relief of the clamping pressure whereby rotation of saidmember relative to said annular part is limited, and a respectiveplurality of surfaces engageable by respective drive surfaces of saidannular part when the tool is clamped between said flange member andtool-fixing member, for joint rotation with said annular part, saidclamping fixture further comprising a detachable locking device forsecuring said flange member to said annular part of said supportingelement in a positive-locking manner in a position of said flange memberin which said flange member is ready to clamp the tool, said lockingdevice including a substantially radially extending resilient tonguemovable between an inactive position and a locking position and formedso that it is moved to said locking position automatically under aspring action.
 2. A clamping fixture according to claim 1, wherein eachof said plurality of stop dogs has a surface located opposite saidlocking surface and defining a surface engageable by a respective drivesurface.
 3. A clamping fixture according to claim 1, wherein saidrolling bodies are balls.
 4. A clamping fixture according to claim 1,wherein said axial stop is formed as an annular shoulder.
 5. A clampingfixture for detachably fixing a disc-like tool to a spindle incooperation with a tool-fixing member, said clamping fixture comprisinga flange member for clamping the tool between said flange member and thetool-fixing member; a supporting element for attaching said flangemember to the spindle in a torque-transmitting relationship and havingan annular part; and a torsion spring having two ends attached to saidflange member and said annular part, respectively, for coupling saidflange member with said annular part for relative axial and rotationaldisplacement therebetween, said annular part having a first end surfaceto be axially supported on the spindle and a second end surface, andsaid flange member having an end surface bearing on said second endsurface of said annular part, said second end surface of said annularpart and said end surface of said flange member having a plurality ofcomplementary sloping end surface portions inclined toward the spindleaxis and defining a wedge angle having a size lying in a self-lockingrange, said annular part including a plurality of stop surfacescorresponding in number to a number of sloping end surface portionsthereof and extending substantially parallel to the spindle axis witheach stop surface adjoining a respective sloping end surface portion ofsaid second end surface at a lower end of said respective sloping endportion and a plurality of drive surfaces corresponding in number to anumber of sloping end surface portions of said annular part, extendingparallel to respective stop surfaces in spaced relationship thereto witheach drive surface arranged in front of an upper end of a respectivesloping end portion of said second end surface, said flange memberhaving a respective plurality of stop dogs extending parallel to thespindle axis at lower ends of respective sloping end surface portions ofsaid flange member and defining each a locking surface engaging arespective stop surface of said annular part upon the axial displacementof said flange member and relief of the clamping pressure wherebyrotation of said member relative to said annular part is limited, and arespective plurality of surfaces engageable by respective drive surfacesof said annular part when the tool is clamped between said flange memberand the tool-fixing member, for joint rotation with said annular part,said clamping fixture further comprising a detachable locking device forsecuring said flange member to said annular part of said supportingelement in a positive-locking manner in a position of said flange memberin which said flange member is ready to clamp the tool, said annularpart having a plurality of catch recesses corresponding in number to thenumber of sloping surfaces and adjoining said sloping surfaces,respectively, at the lower ends thereof, said catch recesses extendingaxially, being open toward said end surface of said flange member, andhaving opposite end faces defining said stop and drive surfaces,respectively.
 6. A clamping fixture for detachably fixing a disc-liketool to a spindle in cooperation with a tool-fixing member, saidclamping fixture comprising a flange member for clamping the toolbetween said flange member and the tool-fixing member; a supportingelement for attaching said flange member to the spindle in atorque-transmitting relationship and having an annular part; and atorsion spring having two ends attached to said flange member and saidannular part, respectively, for coupling said flange member with saidannular part for relative axial and rotational displacementtherebetween, said annular part having a first end surface to be axiallysupported on the spindle and a second end surface, and said flangemember having an end surface bearing on said second end surface of saidannular part, said second end surface of said annular part and said endsurface of said flange member having a plurality or complementarysloping end surface portions inclined toward the spindle axis anddefining a wedge angle having a size lying in a self-locking range, saidannular part including a plurality of stop surfaces corresponding innumber to a number of sloping end surface portions thereof and extendingsubstantially parallel to the spindle axis with each stop surfaceadjoining a respective sloping end surface portion of said second endsurface at a lower end of said respective sloping end portion and aplurality of drive surfaces corresponding in number to a number ofsloping end surface portions of said annular part, extending parallel torespective stop surfaces in spaced relationship thereto with each drivesurface arranged in front of an upper end of a respective sloping endportion of said second end surface, said flange member having arespective plurality of stop dogs extending parallel to the spindle axisat lower ends of respective sloping end surface portions of said flangemember and defining each a locking surface engaging a respective stopsurface of said annular part upon the axial displacement of said flangemember and relief of the clamping pressure whereby rotation of saidmember relative to said annular part is limited, and a respectiveplurality of surfaces engageable by respective drive surfaces of saidannular part when the tool is clamped between said flange member and thetool-fixing member, for joint rotation with said annular part, saidclamping fixture further comprising a detachable locking device forsecuring said flange member to said annular part of said supportingelement in a positive-locking manner in a position of said flange memberin which said flange member is ready to clamp the tool, said annularpart having a substantially inverted pot-shaped cross-section, includinga cylindrical portion having an end surface facing said flange memberand defining said end surface thereof on which said sloping surfaceportions are formed, said cylindrical portion having a wall having aplurality of apertures defining, respectively, said plurality of catchrecesses.
 7. A clamping fixture for detachably fixing a disc-like toolto a spindle in cooperation with a tool-fixing member, said clampingfixture comprising a flange member for clamping the tool between saidflange member and the tool-fixing member; a supporting element forattaching said flange member to the spindle in a torque-transmittingrelationship and having an annular part; and a torsion spring having twoends attached to said flange member and said annular part, respectively,for coupling said flange member with said annular part for relativeaxial and rotational displacement therebetween, said annular part havinga first end surface to be axially supported on the spindle and a secondend surface, and said flange member having an end surface bearing onsaid second end surface of said annular part, said second end surface ofsaid annular part and said end surface of said flange member having aplurality of complementary sloping end surface portions inclined towardthe spindle axis and defining a wedge angle having a size lying in aself-locking range, said annular part including a plurality of stopsurfaces corresponding in number to a number of sloping end surfaceportions thereof and extending substantially parallel to the spindleaxis with each stop surface adjoining a respective sloping end surfaceportion of said second end surface at a lower end of said respectivesloping end portion and a plurality of drive surfaces corresponding innumber to a number of sloping end surface portions of said annular part,extending parallel to respective stop surfaces in spaced relationshipthereto with each drive surface arranged in front of an upper end of arespective sloping end portion of said second end surface, said flangemember having a respective plurality of stop dogs extending parallel tothe spindle axis at lower ends of respective sloping end surfaceportions of said flange member and defining each a locking surfaceengaging a respective stop surface of said annular part upon the axialdisplacement of said flange member and relief of the clamping pressurewhereby rotation of said member relative to said annular part islimited, and a respective plurality of surfaces engageable by respectivedrive surfaces of said annular part when the tool s clamped between saidflange member and the tool-fixing member, for joint rotation with saidannular part, said clamping fixture further comprising a detachablelocking device for securing said flange member to said annular part ofsaid supporting element in a positive-locking manner in a position ofsaid flange member in which said flange member is ready to clamp thetool; and a plurality of recessed grooves arranged between said secondend surface of said annular part and said end surface of said flangemember, and a respective plurality of rolling bodies located in saidrecessed grooves.
 8. A clamping fixture for detachably fixing adisc-like tool to a spindle in cooperation with a tool-fixing member,said clamping fixture comprising a flange member for clamping the toolbetween said flange member and tool-fixing member; a supporting elementfor attaching said flange member to the spindle in a torque-transmittingrelationship and having an annular part; and a torsion spring having twoends attached to said flange member and said annular part, respectively,for coupling said flange member with said annular part for relativeaxial and rotational displacement therebetween, said annular part havinga first end surface to be axially supported on the spindle and a secondend surface, and said flange member having an end surface bearing onsaid second end surface of said annular part, said second end surface ofsaid annular part and said end surface of said flange member having aplurality of complementary sloping end surface portions inclined towardthe spindle axis and defining a wedge angle having a size lying in aself-locking range, said annular part including a plurality of stopsurfaces corresponding in number to a number of sloping end surfaceportions thereof and extending substantially parallel to the spindleaxis with each stop surface adjoining a respective sloping end surfaceportion of said second end surface at a lower end of said respectivesloping end portion and a plurality of drive surfaces corresponding innumber to a number of sloping end surface portions of said annular part,extending parallel to respective stop surfaces in spaced relationshipthereto with each drive surface arranged in front of an upper end of arespective sloping end portion of said second end surface, said flangemember having a respective plurality of stop dogs extending parallel tothe spindle axis at lower ends of respective sloping end surfaceportions of said flange member and defining each a locking surfaceengaging a respective stop surface of said annular part upon the axialdisplacement of said flange member and relief of the clamping pressurewhereby rotation of said member relative to said annular part islimited, and a respective plurality of surfaces engageable by respectivedrive surfaces of said annular part when the tool is clamped betweensaid flange member and the tool-fixing member, for joint rotation withsaid annular part, said clamping fixture further comprising a detachablelocking device for securing said flange member to said annular part ofsaid supporting element in a positive-locking manner in a position ofsaid flange member in which said flange member is ready to clamp thetool; and a cylindrical sleeve, said flange body being fixed within saidcylindrical sleeve, said cylindrical sleeve having an axial stop forengaging said annular part to prevent its loosening in an axialdirection toward the tool.
 9. A clamping fixture for detachably fixing adisc-like tool to a spindle in cooperation with a tool-fixing member,said clamping fixture comprising a flange member for clamping the toolbetween said flange member and the tool-fixing member; a supportingelement for attaching said flange member to the spindle in atorque-transmitting relationship and having an annular part; and atorsion spring having two ends attached to said flange member and saidannular part, respectively, for coupling said flange member with saidannular part for relative axial and rotational displacementtherebetween, said annular part having a first end surface to be axiallysupported on the spindle and a second end surface, and said flangemember having an end surface bearing on said second end surface or saidannular part, said second end surface of said annular part and said endsurface of said flange member having a plurality of complementarysloping end surface portions inclined toward the spindle axis anddefining a wedge angle having a size lying in a self-locking range, saidannular part including a plurality of stop surfaces corresponding innumber to a number of sloping end surface portions thereof and extendingsubstantially parallel to the spindle axis with each stop surfaceadjoining a respective sloping end surface portion of said second endsurface at a lower end of said respective sloping end portion and aplurality of drive surfaces corresponding in number to a number ofsloping end surface portions of said annular part, extending parallel torespective stop surfaces in spaced relationship thereto with each drivesurface arranged in front of an upper end of a respective sloping endportion of said second end surface, said flange member having arespective plurality of stop dogs extending parallel to the spindle axisat lower ends of respective sloping end surface portions of said flangemember and defining each a locking surface engaging a respective stopsurface of said annular part upon the axial displacement of said flangemember and relief of the clamping pressure whereby rotation of saidmember relative to said annular part is limited, and a respectiveplurality of surfaces engageable by respective drive surfaces of saidannular part when the tool is clamped between said flange member and thetool-fixing member, for joint rotation with said annular part, saidclamping fixture further comprising a detachable locking device forsecuring said flange member to said annular part of said supportingelement in a positive-locking manner in a position of said flange memberin which said flange member is ready to clamp the tool, said lockingdevice including a substantially radially extending resilient tonguereceived in one of said catch recesses of said annular part between arespective stop surface and a respective stop dog received in said onecatch recess in the position of said flange member in which said flangemember is ready to clamp the tool to secure said flange member to saidannular part for joint rotation, said resilient tongue, in inactiveposition, of said locking device, being movable axially towards saidpart and out of a path of said respective stop dog to release saidrespective stop dog, said resilient tongue overlapping said stop dog ina peripheral direction in the inactive position of the locking device.10. A clamping fixture according to claim 5, wherein each of said catchrecesses has a width measured in a peripheral direction, each of saidstop dogs being received in a respective catch recess and having a widthwhich is less than the width of the respective catch recess.
 11. Aclamping fixture according to claim 1, wherein said annular part has asubstantially inverted pot-shaped cross-section, including a cylindricalportion having an end surface facing said flange member and definingsaid end surface thereof on which said sloping surface portions areformed.